158 research outputs found
Paradoxes of neutrino oscillations
Despite the theory of neutrino oscillations being rather old, some of its
basic issues are still being debated in the literature. We discuss, in the
framework of the wave packet approach, a number of such issues, including the
relevance of the "same energy" and "same momentum" assumptions, the role of
quantum-mechanical uncertainty relations in neutrino oscillations, the
dependence of the production/detection and propagation coherence conditions
that ensure the observability of neutrino oscillations on neutrino energy and
momentum uncertainties, the question of (in)dependence of the oscillation
probabilities on the neutrino production and detection processes, the
applicability limits of the stationary source approximation, and Lorentz
invariance of the oscillation probability. We also develop a novel approach to
calculation of the oscillation probability in the wave packet picture, based on
the summation/integration conventions different from the standard one, which
gives a new insight into the oscillation phenomenology. We discuss a number of
apparently paradoxical features of the theory of neutrino oscillations.Comment: LaTeX, 45 pages, no figures. v2: references adde
Flavor symmetry analysis of charmless B --> VP decays
Based upon flavor SU(3) symmetry, we perform global fits to charmless
B decays into one pseudoscalar meson and one vector meson in the final
states. We consider different symmetry breaking schemes and find that the one
implied by na{\"i}ve factorization is slightly favored over the exact symmetry
case. The vertex of the unitarity triangle (UT)
constrained by our fits is consistent with other methods within errors. We have
found large color-suppressed, electroweak penguin and singlet penguin
amplitudes when the spectator quark ends up in the final-state vector meson.
Nontrivial relative strong phases are also required to explain the data. The
best-fit parameters are used to compute branching ratio and CP asymmetry
observables in all of the decay modes, particularly those in the decays
to be measured at the Tevatron and LHC experiments.Comment: 23 pages and 2 plots; updated with ICHEP'08 data and expanded in
discussions and reference
Baryon magnetic moments in the QCD string approach
Magnetic moments of baryons composed of light and strange quarks are computed
for the first time through the only parameter of the model -- string tension
. Resulting theoretical values differ from the experimental ones
typically by about
10%.Comment: LaTeX, 13 pages; misprints are correcte
Di-Pion Decays of Heavy Quarkonium in the Field Correlator Method
Mechanism of di-pion transitions in
bottomonium and charmonium is studied with the use of the chiral
string-breaking Lagrangian allowing for the emission of any number of
and not containing fitting parameters. The transition amplitude
contains two terms, , where first term (a) refers to subsequent one-pion
emission: and second term
(b) refers to two-pion emission: . The one-parameter formula for the di-pion mass
distribution is derived, (phase space) , where
. The
parameter dependent on the process is calculated, using SHO wave
functions and imposing PCAC restrictions (Adler zero) on amplitudes a,b. The
resulting di-pion mass distributions are in agreement with experimental data.Comment: 62 pages,8 tables,7 figure
New Glueball-Meson Mass Relations
Using the ``glueball dominance'' picture of the mixing between q\bar{q}
mesons of different hidden flavors, we establish new glueball-meson mass
relations which serve as a basis for glueball spectral systematics. For the
tensor glueball mass 2.3\pm 0.1 GeV used as an input parameter, these relations
predict the following glueball masses: M(0^{++})\simeq 1.65\pm 0.05 GeV,
M(1^{--})\simeq 3.2\pm 0.2 GeV, M(2^{-+})\simeq 2.95\pm 0.15 GeV,
M(3^{--})\simeq 2.8\pm 0.15 GeV. We briefly discuss the failure of such
relations for the pseudoscalar sector. Our results are consistent with
(quasi)-linear Regge trajectories for glueballs with slope \simeq 0.3\pm 0.1
GeV^{-2}.Comment: Extensive revision including response to comments received, value of
glueball Regge slope, and a consideration of radial excitations. 14 pages,
LaTe
Uniform semiclassical trace formula for U(3) --> SO(3) symmetry breaking
We develop a uniform semiclassical trace formula for the density of states of
a three-dimensional isotropic harmonic oscillator (HO), perturbed by a term
. This term breaks the U(3) symmetry of the HO, resulting in a
spherical system with SO(3) symmetry. We first treat the anharmonic term in
semiclassical perturbation theory by integration of the action of the perturbed
periodic HO orbits over the manifold P which characterizes
their 4-fold degeneracy. Then we obtain an analytical uniform trace formula
which in the limit of strong perturbations (or high energy) asymptotically goes
over into the correct trace formula of the full anharmonic system with SO(3)
symmetry, and in the limit (or energy) restores the HO trace
formula with U(3) symmetry. We demonstrate that the gross-shell structure of
this anharmonically perturbed system is dominated by the two-fold degenerate
diameter and circular orbits, and {\it not} by the orbits with the largest
classical degeneracy, which are the three-fold degenerate tori with rational
ratios of radial and angular frequencies. The same
holds also for the limit of a purely quartic spherical potential .Comment: LaTeX (revtex4), 26pp., 5 figures, 1 table; final version to be
published in J. Phys. A (without appendices C and D
Massive Electrodynamics and the Magnetic Monopoles
We investigate in detail the problem of constructing magnetic monopole
solutions within the finite-range electrodynamics (i.e., electrodynamics with
non-zero photon mass, which is the simplest extension of the standard theory;
it is fully compatible with the experiment). We first analyze the classical
electrodynamics with the additional terms describing the photon mass and the
magnetic charge; then we look for a solution analogous to the Dirac monopole
solution. Next, we plug the found solution into the Schr\"{o}dinger equation
describing the interaction between the the magnetic charge and the electron.
After that, we try to derive the Dirac quantization condition for our case.
Since gauge invariance is lost in massive electrodynamics, we use the method of
angular momentum algebra. Under rather general assumptions we prove the theorem
that the construction of such an algebra is not possible and therefore the
quantization condition cannot be derived. This points to the conclusion that
the Dirac monopole and the finite photon mass cannot coexist within one and the
same theory. Some physical consequences of this conclusion are considered. The
case of t'Hooft-Polyakov monopole is touched upon briefly.Comment: 24 pages, revtex, 1 figure appended as a PostScript fil
Resonant Two-body D Decays
The contribution of a resonance to is
calculated by applying the soft pion theorem to , and is
found to be about 30% of the measured amplitude and to be larger than the
component of this amplitude. We estimate a 70% contribution to
the total amplitude from a higher resonance. This implies large
deviations from factorization in D decay amplitudes, a lifetime difference
between D^0 and D^+, and an enhancement of mixing due to SU(3)
breaking.Comment: To be published in Physical Review Letters, some corrections,
references update
Constraint on axial-vector meson mixing angle from nonrelativistic constituent quark model
In a nonrelativistic constituent quark model we find a constraint on the
mixing angle of the strange axial-vector mesons, determined solely by two parameters: the
mass difference of the and mesons and the ratio of the constituent
quark masses.Comment: 8 pages, LaTe
Electromagnetic transition form factors of negative parity nucleon resonances
We have calculated the transition form factors for the electromagnetic
excitation of the negative parity resonances of the nucleon using different
models previously proposed and we discuss their results and limits by
comparison with experimental data.Comment: 13 pages, 6 figures, to be published on Journal of Physics
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